Summary

A vulnerability in the Internet Group Management Protocol (IGMP) packet-processing functionality of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust buffers on an affected device, resulting in a denial of service (DoS) condition.

The vulnerability is due to the affected software insufficiently processing IGMP Membership Query packets that are sent to an affected device. An attacker could exploit this vulnerability by sending a large number of IGMP Membership Query packets, which contain certain values, to an affected device. A successful exploit could allow the attacker to exhaust buffers on the affected device, resulting in a DoS condition that requires the device to be reloaded manually.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

For more information about which Cisco IOS XE Software releases are vulnerable, see the Fixed Software section of this advisory.

Assessing the IP Multicast Routing Configuration

To determine whether IP multicast routing is configured for a device, administrators can log in to the device and use the include ip multicast-routing directive in the CLI to check for the presence of the ip multicast-routing command in the device configuration.

The following examples show the output of the include ip multicast-routing directive for devices that are configured to support IP multicast routing:

Determining the Cisco IOS XE Software Release

To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS Software, Cisco IOS XE Software, or similar text.

The following example shows the output of the command for a device that is running Cisco IOS XE Software Release 16.2.1 and has an installed image name of CAT3K_CAA-UNIVERSALK9-M:

Products Confirmed Not Vulnerable

No other Cisco products are currently known to be affected by this vulnerability.

Cisco has confirmed that this vulnerability does not affect Cisco IOS Software, Cisco IOS XR Software, or Cisco NX-OS Software.

Workarounds

There are no workarounds that address this vulnerability.

Fixed Software

Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.

When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.

In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.

Cisco IOS and IOS XE Software

To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides a tool, the Cisco IOS Software Checker, that identifies any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified (“Combined First Fixed”).

Customers can use this tool to perform the following tasks:

Initiate a search by choosing one or more releases from a drop-down list or uploading a file from a local system for the tool to parse

Enter the output of the show version command for the tool to parse

Create a custom search by including all previously published Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication

To determine whether a release is affected by any published Cisco Security Advisory, use the Cisco IOS Software Checker on Cisco.com or enter a Cisco IOS Software or Cisco IOS XE Software release—for example, 15.1(4)M2 or 3.13.8S—in the following field:

Exploitation and Public Announcements

The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

This vulnerability was found during the resolution of a Cisco TAC support case.

Cisco Security Vulnerability Policy

To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Cisco Security Vulnerability Policy

To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.